Short/Branched Chain Acyl-CoA Dehydrogenase Deficiency

Other Names


2MBCD deficiency

2-methylbutyryl CoA dehydrogenase deficiency


Diagnosis Coding

E71.312, Short chain acyl CoA dehydrogenase deficiency

Disorder Category

An organic acidemia



Elevated C5 (isovaleryl carnitine)

Tested By

Tandem mass spectrometry (MS/MS); sensitivity=NA; specificity=NA


Deficiency of 2-methylbutyryl-CoA dehydrogenase results in the inability to break down isoleucine causing an organic acidemia. This condition is typically found by newborn screening and its clinical significance is still unclear. Some of the initially reported patients had neurological symptoms, but their relationship to the metabolic defect remains unclear. It is now considered a biochemical variant usually with a benign clinical course.


The condition is rare; less than 20 cases have been reported, primarily among the Hmong population. [Short/Branched Chain Acyl-CoA Dehydrogenase Deficiency - Information for Professionals (STAR-G)] More and more cases have been identified by neonatal screening, but they are not published given the benign clinical course.


Autosomal recessive

Prenatal Testing

DNA testing or enzyme analysis by amniocentesis or CVS. Prenatal diagnosis is usually not performed given the benign nature of this condition.

Clinical Characteristics

With or without treatment, most patients have no clinically significant abnormalities. Symptoms may be triggered by fasting or illness.

Initial signs/symptoms may include:
  • Nausea
  • Vomiting
  • Irritability
  • Hypoglycemia
  • Lethargy
Treatment consists of carnitine supplementation and fasting avoidance. Again, the need for treatment is unclear and continued follow-up and monitoring of these patients seems at present the best course of action.

Follow-up Testing after Positive Screen

Quantitative plasma acylcarnitine profile, urine organic acids, urine acylglycine. Urine acylglycine analysis is necessary to exclude this condition.

Primary Care Management

Upon Notification of the + Screen

  • Contact the family and evaluate the infant for poor feeding, lethargy, vomiting.
  • Provide emergency treatment/referral for symptoms of vomiting, lethargy or seizures.
  • To confirm the diagnosis, work with the following service(s): see all Newborn Screening Programs services providers (22) in our database.
  • For evaluation and ongoing collaborative management, consult the following service(s): see all Pediatric Genetics services providers (3) in our database.

If the Diagnosis is Confirmed

Specialty Care Collaboration

Initial consultation and ongoing collaboration, particularly for dietary management. Genetic counseling for the family.


Information & Support

For Professionals

Short/Branched Chain Acyl-CoA Dehydrogenase (OMIM)
Extensive review of literature that provides technical information on genetic disorders; Online Mendelian Inheritance in Man site, hosted by Johns Hopkins University.

Genetics in Primary Care Institute (AAP)
The goal of this site is to increase collaboration in the care of children with known or suspected genetic disorders. It includes health supervision guidelines and other useful resources; represents a collaboration among the Health Resources & Services Administration, the Maternal and Child Health Bureau, and the American Academy of Pediatrics.

For Parents and Patients


Organic Acidemia Association (OAA)
A nonprofit organization that provides information, support, events, connections with other parents, a discussion board, and nutrition and recipe ideas.


2-Methylbutyryl-CoA Dehydrogenase Deficiency (Genetics Home Reference)
Also known as short/branched chain acyl-CoA dehydrogenase deficiency. Excellent, detailed review of condition for patients and families; U.S. National Library of Medicine.

2-Methylbutyryl CoA Dehydrogenase Deficiency - Information for Parents (STAR-G)
A fact sheet, written by a genetic counselor and reviewed by metabolic and genetic specialists, for families who have received an initial diagnosis of this newborn disorder; Screening, Technology and Research in Genetics.

Baby's First Test (Genetic Alliance)
A clearinghouse for newborn screening information. Provides resources about screening at the local, state, and national levels and ways for people to share their viewpoints and questions about newborn screening; supported by the U.S. Department of Health and Human Services.

Organic Acidemia Association (OAA)
A nonprofit organization that provides information, support, events, connections with other parents, a discussion board, and nutrition and recipe ideas.

Center for Parent Information and Resources (CPIR)
Maintains a large resource library with information related to children with disabilities. Parent Information Centers in every state provide training to parents of children with disabilities and provide information about local conferences, support groups, and finding schools and other local services. Department of Education, Office of Special Education.


ACT Sheet for Elevated C5 Acylcarnitine (ACMG) (PDF Document 348 KB)
Contains short-term recommendations for clinical follow-up of the newborn who has screened positive; American College of Medical Genetics.

Confirmatory Algorithms for Elevated C5 Acylcarnitine (ACMG)
An algorithm of the basic steps involved in determining the final diagnosis of an infant with a positive newborn screen; American College of Medical Genetics.


Genetics clinic services throughout the US can be found through the Genetics Clinic Services Search Engine (ACMG).

Newborn Screening Programs

See all Newborn Screening Programs services providers (22) in our database.

Pediatric Genetics

See all Pediatric Genetics services providers (3) in our database.

For other services related to this condition, browse our Services categories or search our database.

Helpful Articles

PubMed search for short/branched chain acyl-CoA dehydrogenase deficiency and neonatal screening, last 5 years.

Alfardan J, Mohsen AW, Copeland S, Ellison J, Keppen-Davis L, Rohrbach M, Powell BR, Gillis J, Matern D, Kant J, Vockley J.
Characterization of new ACADSB gene sequence mutations and clinical implications in patients with 2-methylbutyrylglycinuria identified by newborn screening.
Mol Genet Metab. 2010;100(4):333-8. PubMed abstract / Full Text

Van Calcar SC, Baker MW, Williams P, Jones SA, Xiong B, Thao MC, Lee S, Yang MK, Rice GM, Rhead W, Vockley J, Hoffman G, Durkin MS.
Prevalence and mutation analysis of short/branched chain acyl-CoA dehydrogenase deficiency (SBCADD) detected on newborn screening in Wisconsin.
Mol Genet Metab. 2013;110(1-2):111-5. PubMed abstract / Full Text

Authors & Reviewers

Initial Publication: December 2007; Last Update: July 2018
Current Authors and Reviewers (click on name for bio):
Author: Nicola Longo, MD, Ph.D.
Reviewers: Nicola Longo, MD, Ph.D.